The present invention related generally to mechanical mounting devices suitable for use with agricultural tractors and more particularly to an adjusting device for a three-point mounting system including a draft link used for connecting agricultural implements onto a tractor.
Mounting devices for agricultural tractors usually are required to include means to facilitate adjustment of the mounting means in order to enable different types of implements to be suitably placed in operative mounting arrangement on the tractor. In the prior art, devices are available which enable adjustment of the space between the ends of rear draft links of mounting systems thereby to facilitate the adjustment of the mounting system to handle different implements. For example, it has been proposed to equip each draft link of a mounting system with a separate hydraulic cylinder in order to facilitate the adjustment or shifting of the draft link of the tractor mounting arrangement. (German Offenlegungsschrift No. 1,557,845). However, systems of this type involve a disadvantage in that the use of hydraulic equipment and the necessary control valves and lines which accompany such equipment tend to be very cumbersome. Furthermore, hydraulic control units and other similar elements will be exposed to damage because of their location on the tractor in close proximity to the soil. Furthermore, such hydraulic systems must be made with the capability of absorbing high impact stresses due to shocks which may be received during operation with a heavy tractor implement. Generally, such impact forces can be significantly higher than operational stresses which may arise from the inherent design of the equipment. If such impact stresses are not counteracted by relatively expensive and cumbersome measures, malfunctioning or other undesirable operational problems may be anticipated in the hydraulic system of the tractor.
The present invention is therefore directed toward providing an improved assembly for mounting implements on a tractor, and particularly to an improved adjusting device for the draft links of the three-point mounting systems for agricultural tractors which is relatively simple in design and which ensures that penetration by dirt or other deleterious material will not adversely affect the operability of the device during the performance of rough agricultural operations.